Photographic processing apparatus and method



A. J. SABLE April 12, 1966 PHOTOGRAPHIC PROCESSING APPARATUS AND METHOD 2 Sheets-Sheet 1 Original Filed Sept. 19, 1962 FIG.

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PHOTOGRAPHIC PROCESSING APPARATUS AND METHOD April 12, 1966 2 Sheets-Sheet 2 Original Filed Sept. 19, 1962 INVEN OR.

%.4 ATTORNEYS United States Patent 3,245,335 PHOTOGRAPHIC PRGCESSING APPARATUS AND METHOD Arthur J. Sable, Riverside, Conn, assignor to Polaroid Corporation, Cambridge, Mass, a corporation of Delaware Continuation of application Ser. No. 224,644, Sept. 19, 1962. This application Mar. 18, 1965, Ser. No. 444,914

14 Claims. (Cl. 9589) This application is a continuation of my application -Serial No. 224,644, filed September 19, 1962, now abandoned.

This invention relates to photographic processing apparatus for distributing a liquid in contact with a photographic sheet and methods performed thereby; and particularly to apparatus including a pair of juxtaposed pressure-applying members for and methods of distributing a liquid between a pair of superposed photographic sheets.

In US. Patent No. 2,647,056, issued July 28, 1953, in the name of Edwin H. Land, there is shown and described a method of producing a photographic transfer image in volving the movement of a pair of sheets in superposition between a pair of juxtaposed members for distributing a viscous processing liquid between and in contact with the sheets. The pressure-applying members, while shown as rolls in the above patent, may take a number of different forms, but generally comprise a pair of members having adjacent surfaces defining a convergent passage or gap between them through which the sheets are moved relative to the members for advancing or spreading a quantity of a processing liquid, usually quite viscous, relative to, between and in contact with the sheets in a direction opposite the direction of movement of the sheets relative to the members. The pressure-applying members may be movable with respect to one another and biased, e.g., by springs toward one another; and/or the two members may be fixed against movement more than a predetermined distance apart so that the maximum width of the gap between the members is fixedly predetermined.

During distribution of the processing liquid in this manner, hydraulic pressure is generated within the mass of the liquid being advanced relative to and between the sheets; and this pressure tends to force the sheets and the pressure-applying members apart from one another. Heretofore it has been the practice to mount the pressureapplying members in the vicinity of their ends, i.e., near the lateral edges of the sheets, particularly in the case of rolls; and to apply any bias to the members at or in the region in the means mounting the members with this type of mounting of the pressure-applying members, even though the hydraulic pressure within the liquid may be uniform from side to side of the sheets, the resultant force or bending moment acts upon the medial portions of the two members, causing the two members to bow apart and this results in a gap between the members which is not uniform, being wider at its mid-portion, i.e., the mid-portions of the sheets, than at its ends, i.e., the lateral edges of the sheets. This, of course, may result in such an uneven distribution of the liquid as to adversely affect or even prevent processing in some areas of the sheets.

The magnitude'of this problem varies with a number of factors, particularly the width of the sheets to be treated with the liquid; while variations in the thickness of the layer of the liquid which remains between the sheets becomes more critical as such layers become thinner. The answer to this problem has been to employ pressure-apply ing members which are stronger and are more rigid, and is achieved by providing larger and bulkier members and/ or employing stronger and more expensive materials for the members. Both of these answers have proved less Patented Apr. 12, lgfifi than completely satisfactory from the point of view of performance as well as for reasons of size, weight and economy.

An object of the present invention is to provide novel and improved pressure-applying apparatus for and methods of distributing a processing liquid in contact with a photographic sheet.

Other objects of the invention are: to provide apparatus and methods of the type described wherein a pair of juxtaposed pressure-applying members are biased toward one another so as to insure uniformity of distribution of the processing liquid; to provide an apparatus and method wherein the pressure-applying members are biased toward one another by a force which is uniformly distributed throughout the length of one of the members; and to pro vide pressure-applying means as described in which the member which is biased toward the other member is sulficiently flexible to permit it to conform to deflections in the other member.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the apparatus possessing the construction, combination of elements and arrangement of parts, and the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIGURE 1 is a somewhat schematic, sectional view of a pair of pressure-applying members illustrating the distribution of a liquid between a pair of superposed sheets;

FIG. 2 is a sectional view illustrating, somewhat schematically, apparatus embodying the invention and for performing the method thereof; and

FIGS. 3 through 6 are fragmentary perspective views of other embodiments of the apparatus.

Reference is made to FIGURE 1 of the drawings in which there is illustrated a pair of juxtaposed pressureapplying members in the form of a cylindrical roll iii and a bar 12 having a plane surface disposed parallel with a plane tangent to the surface of roll 10 and cooperating with the surface of roll 10 to define a converging passage or gap between the roll and bar. The operation of any two pressure-applying members embodying the invention is substantially the same regardless of the particular construction of the members, that is, whether they be rolls which may rotate or remain stationary, a bar and roll as shown, two rolls, or two bars or similar members having non-circular cross sections and not designed to rotate. A pair of sheets, designated 14 and 16, are moved into superposition through the convergent passage between roll 10 and bar 12 to efiect the distribution of a processing liquid between the sheets. The liquid may be provided initially between the sheets in a number of different ways, for example, from a rupturable container mounted on one of the sheets, from a container which is moved relative to and across one of the sheets while its fiuid contents are dispensed onto the sheet, or from a fixed device such as a nozzle which dispenses the liquid continuously. The liquid designated 18, provided between the sheets, collects in a mass in the form of a meniscus at the convergent entrance portion of the passage between the pressure-applying members (as shown) during movement of the sheets relative to and between the pressure-applying members.

The sheets and processing liquid, in a preferred form, may comprise materials and reagents for producing positive photographic prints by a silver halide diffusion-transfer reversal process such as is described in detail in US. Patent 2,543,181, issued February 27, 1951, in the name of Edwin H. Land, in which case one of the sheets may comprise a gelatino silver halide emulsion carried on a flexible support, the other sheet comprises a layer for supporting a silver transfer image, and the processing liquid includes a silver halide developer and a silver halide solvent. The liquid, as indicated in the aforementioned patents, is preferably quite viscous, having a viscosity in excess of 1,060 centipoises of 24 C. It is this viscosity which facilitates the uniform distribution of the liquid and also contributes to the generation of hydraulic pressure within the liquid between the sheets as the liquid is being distributed.

By distribution of the liquid during and in response to movement of the sheets relative to and between the pressure-applying members, is meant that the mass of the liquid is moved relative to, between and in contact with those areas of the inner surfaces of the sheets to be treated, in a direction opposite the direction of movement of the sheets. The mass of the liquid may and usually does remain substantially stationary with respect to the pressure-applying members. In a photographic process particularly useful in document copying, distribution of the liquid is intended primarily to effect the wetting of the inner surfaces of one or both sheets which absorb reagents from the mass of viscous liquid as the latter is moved relative to and in contact with the sheets. However, even though the purpose of the liquid distribution process may not be to spread the liquid in a layer between the superposed sheets, the viscosity-providing agent in the liquid (e.g., sodium carboxymethyl cellulose) is a filmforming agent and as such tends to adhere to the sheets and form a layer which may be extremely thin. This layer, however thin, is formed between the sheets and performs the function of retaining the sheets in superposition during the period required for processing, i.e., formation of a transfer image.

The processing liquid is initially provided between the sheets as a mass preferably uniformly distributed across the sheets. With a uniform distribution of the mass of fluid, the force exerted on the pressure-applying members due to the hydraulic pressure generated within the mass of the liquid is also uniformly distributed across the sheets and throughout the length of the pressure-applying members. The resulting bending moment on the pressureapplying members, however, is effectively located midway between the sides of the sheets or, more specifically, substantially midway between the ends of the mass of liquid, thereby causing the pressure-applying members to bow apart at their mid-portions. This bowing, of course, becomes increasingly pronounced as the width of the sheets is increased while the amount of bowing which can be tolerated becomes less as the thickness of the layer of liquid spread between the sheets is reduced.

Reference is now made to FIG. 2 of the drawings wherein there is illustrated fluid-distributing apparatus embodying the invention. This apparatus comprises an elongated roll 20 and a juxtaposed bar 22 both having cross sections which are substantially the same as the cross sections of roll and bar 12 respectively. Roll is provided with stub shafts 24 at its ends journaled in a pair of support members 26 and is rotatable about its axis. Bar 22 is mounted between support members 26 for movement toward and away from roll 20, and the ends of bar 22 are preferably engaged with support members 26 in a manner which constrains the bar for movement only in a plane through the axis of roll 20. Roll 20 and bar 22 are shown in FIG. 2 in the relative positions that they would assume during distribution of the processing liquid between a pair of sheets as the latter are moved between the roll and bar, although the sheets themselves have been omitted for purposes of clarity. No attempt is made to construct roll 2t) so that it has sufficient strength and rigidity to resist bending due to hydraulic pressure within the liquid, and accordingly roll 29 bends in the manner shown (to an exaggerated extent) in FIG. 2. This deflection or bending of roll 20 is anticipated, and it is by virtue of the invention that the deflection of roll 20 can occur without adverse effect on the distribution of the processing liquid.

As previously indicated, the deflecting force exerted by the liquid on roll 20 and bar 22 is substantially uniformly distributed throughout the length of the roll and bar so that application of a uniformly distributed force to bar 22 urging the bar toward roll 20 will cause a deflection in bar 22 matching the deflection of roll 20 so that the gap between the bar and roll normally occupied by the sheets and any liquid therebetween will be of uniform thickness throughout its length. This uniform gap is illustrated in FIG. 2 which shows the pressure-applying members in an operating condition but without the sheets and liquid therebetween. As a means for applying a uniformly distributed biasing force to bar 22, there is provided a multiplicity of compression springs 28 mounted between bar 22 and a backing member 30 secured at its ends to support members 26. Springs 28 are distributed at regularly spaced intervals between bar 22 and backing member 30 throughout the length of bar 22, and each of the springs has substantially the same rate as every other spring so that the force exerted thereby on the bar is uniformly distributed and the same throughout the length of the bar.

Bar 22 is sufficiently more flexible than roll 20 so that the bar can be deformed by the force of springs 28 so as to conform to the deflection of roll 20 and the adjacent surfaces of the bar and roll will remain substantially parallel as shown. On the other hand, bar 22 has sufficient rigidity to resist local deformations so that the bar deflects more or less uniformly in the same manner as roll 20, and there are no local areas between the bar and roll where the width of the gap is more or less than in other areas. Backing member 30 may be sufficiently rigid to resist deflection, or it may be constructed in the form shown so that it too deflects, since deflection of the backing member affects only the difference in the extent of deflection of the springs. Backing member 30, being mounted at its ends, deflects, in the same manner as but oppositely from roll 20, since the loading on the backing member by springs 28 is uniform but the deflecting moment acts midway between the ends of the backing member. In the construction shown, springs 28 are deflected or compressed to different extents and are preferably of a relatively low rate so that the force exerted by each of springs 28 is the same as the force exerted by every other spring regardless of the deflections of the springs within the range of normal operation of the apparatus.

Another embodiment of the apparatus is shown in FIG. 3 of the drawings as comprising a roll 20 and bar 22 mounted between support members 26 in the manner described with reference to FIG. 2. The mounting of bar 22 for movement with respect to the rolls can be seen in FIG. 3 and comprises a recess 32 in each of support members 26 in which an end of bar 22 is engaged for sliding movement. The difference between this construction and that previously described resides in the means for applying a uniformly distributed force to bar 22. In the form shown, these means include a backing member 34 mounted at its ends at support members 26 and a spring plate 36 including a section provided with a multiplicity of parallel, uniformly spaced slits 38 which define therebetween a multiplicity of spring fingers 40. Plate 36 is mounted on bar 34, and the spring fingers, which are all parallel to one another, are bent toward bar 22 and turned up at their ends to provide feet located in contact with the surface of bar 22 opposite roll 20. Each of the spring fingers functions as a substantially independent, low-rate cantilever spring and in aggregate the spring fingers provide a uniform, uniformly distributed spring force urging bar 22 toward roll 20.

g A further embodiment of the invention is illustrated in FIG. 4 as comprising a pressure-applying bar 42 mounted at its end onsupport members 44 in generally parallel .relation and spaced from a backing member 46 also supported-at its ends on members 44. Bar 42 provides a pressure-applying surface facing backing member 46, and

,the other pressure-applying member comprises a similar the form of a relatively thin and flexible element 47 -mounted on a resilient, elastically deformable member 49 supported in a backing member in the form of a chan nel 51 and juxtaposed with a relatively rigid pressure member 53. Channel 51 may be formed of sheet metal and is substantially rigid while resilient member 49 is formed of an elastomeric material such as foam rubber which functions as a continuous spring, the compressive force of which is distributed and transmitted to the sheets by flexible element 47. Member 49 comprises a generally parallelepiped-shaped homogeneous body of substantially uniform thickness and compressibility through- .out the portion of its length supporting element 47. The flexible element may be formed of a variety of materials in sheet form, many of the organic plastic such as the linear polyamides (e,g, nylon) being preferred, because of their inexpensiveness, flexibility and low coefficient of friction, and is adhered to resilient member 49 by a suitable cement or adhesive. Resilient member 49 performs the dual functions of movably mounting element 47 and biasing the latter toward pressure member 53.

A form of pressure-applying device designed to be fabricated entirely from resilient sheet material and in which one of the pressure-applying members also comprises the multiplicity of springs is illustrated in FIG. 6 of the drawings. This device comprises a pressure-applying member formed by bending a sheet of resilient material, preferably metal, into a tube having a generally rectangular cross section with one side providing the pressure-applying surface of member 52. Member 52 is supported at its ends by support members 54, and the other pressure-applying member comprises another element formed from sheet material and having a generally C-shaped cross section. This element, generally desig nated 56, includes a base side 58 at which the element is supported on support members 54; a sheet engagement side 60 lying opposite base side 58 and providing the other pressure-applying surface of the device disposed in juxtaposition with the pressure-applying surface of member 52; and a connecting side 62 extending between base side 58 and engagement side 60. Connecting side 62 is formed with a plurality of uniformly spaced narrow slits or slots 64 so that the portions of connecting side 62 intermediate the slots and separated by the slots act as a plurality of individual, independent, low-rate springs mounted on base 58 for biasing sheet engagement side 60 toward pressure-applying member 52. In this embodiment, deflection of both pressure-applying member 52 and base side 58 in opposite directions may be anticipated and does not interfere with the operation of the device.

Since certain changes may be made in the above apparatus and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and n t in a limiting sense.

What is claimed is:

1. Photographic apparatus for distributing a process liquid between a pair of superposed sheets comprising, in combination:

a pair of pressure-applying members each having a sheet engagement surface extending lengthwise of said member;

support means for mounting said members in juxtaposition with said engagement surfaces in face-to-face relation, one of said members being mounted ad jacent the ends of said engagement surface thereof; and

resilient means for applying, to the other of said members, a force substantially uniformly distributed throughout the length of said other member urging said other member toward said one member,

said resilient means comprising a member formed of an elastomer mounted on said support member and engaged between the latter and said other pressureapplying member.

2. Photographic apparatus for distributing a processing liquid between a pair of superposed sheets comprising, in combination:

a pair of pressure-applying members each having a sheet engagement surface extending in a substantially straight line lengthwise of said member;

support means for mounting said members in superposition at the ends of said surfaces with said surfaces in face-to-face relation; and

resilient means for applying to one of said members a multiplicity of substantially independent and equal forces uniformly distributed throughout the length of said one member urging said one member toward said other member;

said resilient means comprising a resilient element mounted on said support means and including a portion formed with a plurality of uniformly spaced parallel slits extending inwardly from one edge to deflne a multiplicity of cantilever springs each located between two of said slits and disposed in engagement with said one pressure-applying member.

3. Photographic apparatus for distributing a processing liquid between a pair of superposed sheets comprising, in combination:

a pair of pressure-applying members each having a sheet engagement surface extending in a substantially straight line lengthwise of said member;

support means for mounting said members in superposition at the end of said surfaces with said surfaces in face-to-face relation; and

resilient means for applying to one of said members multiplicity of substantially independent and equal forces uniformly distributed throughout the length of said one member urging said one member toward said other member;

said other pressure-applying member comprising a roll having a substantially cylindrical pressure-applying, sheet-engagement surface mounted for rotation about the generatrix of said surface;

said sheet engagement surface of said one member including a portion lying in a straight line disposed in a plane through said generatrix.

4. Photographic apparatus for distributing a processing liquid between a pair of superposed sheets comprising,

in combination:

a. first pressure-applying member having a sheet engagement surface extending lengthwise of said member substantially in a straight line;

a second pressure-applying member having a sheet engagement surface extending lengthwise of said member;

an elongated resilient deformable member of substantially uniform resilience and compressibility throughout a length substantially equal to the length of said sheet engagement surface of said second pressureapplying member; and

a backing member mounting said deformable member for juxtaposition with said first pressure-applying member; said second pressure-applying member being mounted on said deformable member with said sheet engagement surface of said second pressure-applying member juxtaposed with said sheet engagement surface of said first pressure-applying member. 5. The photographic apparatus of claim 4 in which said deformable member comprises a body of an elastromeric material having a support surface lying substantially in a straight line, and said second pressure-applying member is relatively thin and flexible and is mounted on said surface of said body.

6. The photographic apparatus of claim 5 in which said backing member is a channel having side walls, said body is secured within said channel between said side walls with a portion of said body including said surface thereof projecting from between said side walls.

7. The photographic apparatus of claim 5 in which said body comprises an elastomeric foam material.

8. A method of uniformly distributing a liquid between and in contact with a :pair of flexible superposed sheets comprising:

superposing .said sheets; providing a quantity of said liquid between said sheets in a mass extending transversely of said sheets;

moving said sheets in superposition together with and mass of liquid relative to and bet-ween a pair of elongated pressure-applying members having juxtaiposed sheet-engagement surfaces and at least one of said members mounted adjacent the ends of said surface thereof; and

applying a multiplicity of substantially equal and efiectively independent forces to said other member substantially uniformly distributed from end-to-end of said other member to urge said other member toward said one member.

9. The method of claim 8 wherein said other member is urged toward said one member by resilient means and is mounted on said resilient means.

10. The method of claim 9 wherein said other member is substantially more flexible than said one member and said resilient means comprise a member formed of an elastomer.

11. The method of claim 9 wherein said surface of said other member is continuous and said other member is urged toward said one member by a plurality of springs each exerting substantially the same force against said other member.

12. The method of claim 9 wherein substantially all of said liquid is squeezed by said members from between said sheets during distribution of said liquid in contact with said sheets.

13. The method of claim 12 wherein said liquid cornprises an aqueous alkaline solution and a thickening agent and said solution is impregnated into at least a layer of one of said sheets during distribution of :said liquid between said sheets.

14. The method of claim 9 wherein said liquid contains a thickening agent and is distributed as a layer of substantially uniform predetermined thickness between said sheets.

References Cit-ed by the Examiner UNITED STATES PATENTS NORTON ANSHER, Primary Examiner. 

1. PHOTOGRAPHIC APPARATUS FOR DISTRIBUTING A PROCESSLIQUID BETWEEN A PAIR OF SUPERPOSED SHEETS COMPRISING, IN COMBINATION: A PAIR OF PRESSURE-APPLYING MEMBERS EACH HAVING A SHEET ENGAGEMENT SURFACE EXTENDING LENGTHWISE OF SAID MEMBER; SUPPORT MEANS FOR MOUNTING SAID MEMBERS IN JUXTAPOSITION WITH SAID ENGAGEMENT SURFACES IN FACE-TO-FACE RELATION, ONE OF SAID MEMBERS BEING MOUNTED ADJACENT THE ENDS OF SAID ENGAGEMENT SURFACE THEREOF; AND RESILIENT MEANS FOR APPLYING, TO THE OTHER OF SAID MEMBERS, A FORCE SUBSTANTIALLY UNIFORMLY DISTRIBUTED THROUGHOUT THE LENGTH OF SAID OTHER MEMBER URGING SAID OTHER MEMBER TOWARD SAID ONE MEMBER, SAID RESILIENT MEANS COMPRISING A MEMBER FORMED OF AN ELASTOMER MOUNTED ON SAID SUPPORT MEMBER AND ENGAGED BETWEEN THE LATTER AND SAID SUPPORT MEMBER AND APPLYING MEMBER. 